The present invention relates to solid, directly-pressable ascorbic acid granulates, processes for their preparation and their use. Such granulates can be used for the preparation of ascorbic acid-containing, solid compositions which contain ascorbic acid as the sole active material or in which ascorbic acid is present as an additive to other adjuvant/active material mixtures.
Ascorbic acid is obtainable not only in crystallized but also in powder form. Both forms are, per se, not directly-pressable, but rather more or less large amounts of adjuvant and additional materials are necessary. Moreover, in order to achieve satisfactory control of the properties of such solid compositions, such as disintegration properties, hardness, mechanical and chemical stability, coloration etc., as a rule, additional materials are needed. However, since ascorbic acid is generally administered in relatively large dosage units, e.g. 500 mg or even 1 g, the addition of large amounts of adjuvant materials leads to undesirably large dosage forms of the compositions.
in the past, granulates and compositions which possess a very high content of ascorbic acid and, nevertheless, display satisfactory properties, have been prepared. Such compositions are described e.g., in the U.S. Pat. Nos. 3,293,132 and G.B. Pat. No. 1,109,186. However, these compositions and the processes for their preparation display some significant disadvantages. Thus, in U.S. Pat. No. 3,293,132, a spray drying process is used, for which powdered ascorbic acid exclusively can be employed. In G.B. Pat. No. 1,109,186, the process requires a starting material of a crystalline ascorbic acid with a precisely defined particle size distribution. In this patent, it is stated that good results cannot be achieved with powdered ascorbic acid or with crystalline ascorbic acid not possessing the narrowly-limited particle size distribution. Finally, in the case of both Patents, the granulates obtained can in no way be directly pressed but rather must be mixed, in a further process step, with additional additives before, e.g., tablets can be pressed therefrom.
In U.S. Pat. No. 3,446,894, ascorbic acid granulates and tablets which possess a content of at least 70 or even 85% ascorbic acid are disclosed. In the Examples, tablets are described with 74.3 and 87.6% ascorbic acid. Compositions with a higher content of ascorbic acid are thus not obtainable. It also follows from the Examples and the patent claims therein that a whole series of adjuvant and additive materials are necessary in order to obtain a stable granulate which then, also again in an additional process step, must be mixed with even more adjuvant agents in order to press tablets therefrom.